In India, as much as 80% of the surface water is polluted resulting mostly from untreated wastewater sludge. Another culprit is industrial waste which comes in the form of dyes and other chemicals that are disposed of during textile production.
Because textile production is widespread across India, finding a remedy for the pollution is a very challenging one. Compounding the problem is the fact that communities rely on river water for bathing and drinking which makes this a significant health hazard that needs a sustainable solution.
Fortunately, a team of designers and biochemical engineers from the University College London have started a project that could potentially address this issue and purify wastewater sludge. They have developed a leaf-shaped tile made of clay and algae infused hydrogel called Indus that is capable of cleaning heavy metals from wastewater sludge. Their hope is that they could manufacture these tiles for use in factory walls or buildings. The wastewater sludge would be collected in a tank which would then be funnelled down by gravity through the channels in the tiles which are laden with algae.
The team travelled across India to study cottage industries from bangle production in Kolkata to textile dyers in Panipat in the hopes of better understanding the source of the pollution. They discovered that different heavy metals are produced depending on the type of dyes or jewelry made. They also found that one particular algae species has been effective in reducing cadmium concentration in the water by about as much as 10 times in just the span of 45 minutes. They then infused this algal species into a seaweed-based hydrogel because not only does it hold the algae in place, but it also acts as a suitable medium for digestion.
The biologic process that makes this possible is called bioremediation. In this process, the algae break down the pollutants in the water thereby cleaning it. This sustainable technique for cleaning wastewater sludge has been used since the 1940s for cleaning up heavily polluted areas. Bioremediation is used by algae, bacteria, and fungus to digest plastics and oils from the water and it has also found its way into commercial products like drain cleaners.
They found a tile manufacturer in Khurja that can produce these tiles to their specifications. They worked with the community to find the best materials and processes that they could use for making Indus cheap and effective. The cost of the tile came out to around $5-7 per square foot depending on the technique used but it is expected to go down in price as they do mass production.
If the project becomes successful, the team hopes to purify wastewater not only across India but in other countries as well. They are exploring materials such as sandcrete, laterite, stone, or processed biosolids as a sustainable foundation for their tiles as they move closer towards the final product.
Although it is still in the early stages, the team hopes that they can someday produce tiles that can eliminate a wide range of heavy metals and purify wastewater sludge using different algae that can target specific contaminants.
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Sources:
https://www.fastcompany.com
https://phys.org/news/